This invention relates to silicon-containing chelating agents. In one aspect, his invention relates to a siliceous surface bearing an organosiloxane chelating agent which is suitable for chelating polyvalent metal ions.
It is well known to treat a siliceous surface, with a suitable hydrolyzable organosilane thereby bonding organic radicals to the siliceous surface. For example, there are currently available certain controlled pore glass supports bearing various organic radicals which are bonded to the glass through Si--O--Si--C bonds to produce protein-active supports. Recently, Leyden, et al., Anal. Chem., 47 (a), pp. 1612 to 1617, August 1975, silylated silica gel with various aminoalkyltrimethoxysilanes to immobilize the various aminoalkyl radicals onto the silica gel. The immobilized aminoalkyl radicals were subsequently derivatized to the corresponding dithiocarbamate and thereafter employed to preconcentrate trace amounts of certain metal ions from dilute solution for subsequent X-ray analysis.
The method of Leyden, et al. is suitable for preparing small amounts of immobilized chelating agents but is less desirable for producing large amounts of said chelating agents. For example, it is undesirable to process a large amount of the support material during the silylating step and again during the subsequent derivatizing step. A more efficient process is desired. There is also a need for inexpensive, immobilized chelating agents for chelating polyvalent metal ions such as calcium ions and magnesium ions.
It is also well known to produce chelating agents which are suitable for chelating polyvalent metal ions such as Ca.sup.+2, by derivatizing certain polyamines such as ethylenediamine with carboxymethyl groups. The resulting chelating agents such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and nitrilotriacetic acid and their salts are readily available.
Prior to this invention, it had not been known or suggested to prepare silicon-containing materials bearing carboxymethyl derivatives of silicon-bonded aminoalkyl radicals, or to bond said materials to a siliceous support.
Herein, aminoalkyl radical means an organic radical bearing at least one nitrogen atom which is bonded to at least one aliphatic carbon atom. Silicon-bonded aminoalkyl radicals are bonded to the silicon through a silicon-carbon bond. By polyvalent metal ions it is meant those metal ions having a positive charge greater than +1 such as Fe.sup.+3, Th.sup.+4, Hg.sup.+2, Cu.sup.+2, Ni.sup.+2, Pb.sup.+2, Zn.sup.+2, Al.sup.+3, Fe.sup.+2, Mn.sup.+2, Ca.sup.+2, Mg.sup.+2, Ba.sup.+2, and the rare earth ions.